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I need a command line utility that enables me to encrypt/decrypt a text file that, due to some circumstances, has to be available online. Encryption does not need to be "super strong" (whatever that is in today's terms), but it would be nice if it was something that a script kiddie couldn't break on his lunchbreak.

Anyone know of something like that?

Needs to work on both XP and '7.

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closed as off topic by random Apr 18 '13 at 0:26

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It does not appear you understand how encrypting a file works. What you want does not exist. – Ramhound Dec 5 '11 at 16:53
@Ramhound - I never said I'm an expert in the area. Is there a reason why such a utility couldn't exist, or are you just unfamiliar with any existing solutions? Your comment isn't very helpful, in any case. – Rook Dec 5 '11 at 17:01

Well, just a quick thought. I think you can use WinRAR's (or 7-Zip's) password encryption on the command line. It should be strong enough. Like this:

rar a -p<password> out.rar <yourpath>\input.txt
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Not a bad idea, but I was more hoping for something in style of "encrypt my-file.txt" / "decrypt my-file.txt my-super-secret-password", that just "switches" the file from encrypted to decrypted, and vice versa. I don't wanna fill my working directory with a bunch of rar files. Nevertheless +1 for thought! – Rook Dec 5 '11 at 2:09
this works with many other archivers 7zip, zip and others.. – Vineet Menon Dec 5 '11 at 7:26

You could always try EFS. It encrypts your file OTF and is bound to your user account. You can use it on multiple computers also, provided they are all Windows. Just embed the EFS certificate of each user account into the file.

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You should mind that relying on a windows certificates does not guarantee you complete safety or integrity of data you want to keep safe. That is because the admin 'key' on windows systems opens everything encrypted with user keys on this system. Hence, your admin could potentialy decrypt your 'safe place'. You did not mentioned the 'online part'. – mnmnc Apr 17 '13 at 22:06

An option to consider is steganography (google it). This encodes your data into some other file (image, audio, video) so in order to retrieve your data somebody has to know that it's in the file to begin with.

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incorrect. steganography is hiding one set of data in another set of data without causing disturbance in the second one. for example hiding text as color offsets in bitmap graphic. it is still in clear text once you know where to find it. You can encrypt the data before embedding it. Steganography would not be my choice as size limitation defeats the purpose of securing a medium to large amount of data. True crypt has command line parametres. I would write a script using wget to download the file and decrypt it with tc. – mnmnc Apr 17 '13 at 22:03

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